Pumps



Jan. 5, 1965 w. G. NICOLL 3,164,097

PUMPS Filed Feb. 9, 1962 2 Sheets-Sheet 1 FIG. I.

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5, 1965 w. L. G. NICOLL 3,164,097

Pum s Filed Feb. 9, 1962 2 Sheets-Sheet 2 FIG. 2.

Walter Lyon Gordon Nl coLL P JW 20 PM y United States Patent M 3,164,097 PUMPS Walter Lyon Gordon Nicoll, 37 Upper Addison Gardens, Kensington, London, England Filed Feb. 9, 1962, Ser. No. 172,152 Claims priority, application Great Britain Feb. 13, 1961 4 Claims. c1.103 97 This invention relates to pumps of centrifugal type, and more particularly to glandless circulating pumps for use in central heating system or the like, i.e. pumps in which the drive for the pump is obtained via a common shaft from a prime mover, usually an electric motor, to which the liquid being pumped has access so that a sealing gland on the drive shaft is not needed.

Such pumps, whether fitted with double sided impellers or alternatively with single sided impellers with the open side towards the inlet, normally have one side of the impeller exposed to the pump inlet and the other to the pump outlet, thus an axial thrust is applied to the drive shaft whenever the pump is operating (due to the pressure rise produced by the pump) and the drive shaft therefor requires a thrust hearing as well as journals. It is usual to fit such a thrust bearing between the pump and motor, where it is notably inaccessible and cannot be adjusted without considerable dismantling of the pump and/ or motor.

It is an object of the present invention to provide an improved circulating pump of the centrifugal type.

According to the invention, there is provided a circulating pump of the centrifugal type having an impeller mounted on one end of a shaft also constituting the shaft of an associated prime mover, in which the impeller is mounted on said shaft with its inlet side towards said prime mover and a single thrust bearing is fitted to said shaft at the far end of the shaft at the opposite end of said prime mover from said impeller, said thrust bearing being adjustible so that the axial position of said shaft and impeller may be varied.

It will be appreciated that, with this arrangement, the thrust bearing is readily accessible and therefore may easily be adjusted, not only without dismantling but if desired without stopping the pump. With such ready access, adjustment of the thrust hearing may be employed whenever it is desired to vary the pumps characteristics, as of course a change in the axial position of the impeller causes alteration of the working clearance between the impeller and a casing in which it operates, so that the pump delivery and output pressure may be set at desired levels.

A further advantage of pumps embodying the invention is found in the fact that the shaft, between the prime mover and the impeller eye, passes through the pump inlet at a minimum pressure zone, and therefore by providing in a wall between the housing of the prime mover and the pump inlet, a journal having grooves parallel to the shaft in its working face a flow of liquid may be drawn from the prime mover. Slots may then be provided in said wall, suitably covered with a mesh filter, to allow liquid to reach the prime mover which thus is not immersed in substantially stagnant liquid but has a steady liquid circulation through it with the advantageous result that any solid particles present are deterred from lodging between working parts of the prime mover with undesirable effects on its performance; the liquid flow also serves to distribute heat from the prime mover, which especially in the case of a prime mover in the form of an electric motor, is of benefit. 1

Pumps embodying the invention furthermore may hav shorter shafts than when the thrust bearing is placed between the impeller and prime mover, and also there is no need for a separate motor baseplate so that the whole apin position by a lock-nut 21.

3,164,997 Patented Jan. 5, 1965 paratus is more compact, and this advantage is secured even when larger shaft journals than usual are employed to give longer periods between overhauls and improved running.

In order that the invention may be well understood, a preferred embodiment thereof will now be described in some detail, reference being made to the accompanying drawing in which:

FIGURE 1 shows somewhat diagrammatically and partly in section one preferred form of pump; and

FIGURE 2 shows similarly a slightly different form of pump.

Referring therefore to FIG. 1 of the drawing, a pump includes an impeller 1, with general radial vanes 2, secured by a nut 3 on a portion 4 of reduced diameter adjacent one end of a shaft 5. The impeller 1 is enclosed in a housing generally indicated at 6 and having a voluteshaped outlet chamber 7 and an inlet chamber 8. It can be noted here that the housing 6 may in practice be made of a plurality of castings bolted or clamped together but in the drawing the exact construction of the housing is not fully shown.

The extreme end 9 of the shaft 5, beyond impeller 1, is carriedin a journal 10 on the base wall of the outlet chamber 7. This journal is of advantage but is not essential. The shaft'S extends from the impeller 1 through a relatively large hole 11 in another wall between the volute-shaped chamber 7 and inlet chamber 6, accommodating an eye 2a, on the impeller 2, through said inlet chamber, and through a further journal 12 in another wall of said inlet chamber 8 to a motor chamber 13 containing an electric motor whose armature 14 is carried by said shaft 5. Said motor chamber 13 is enclosed by a motor sleeve 15 carrying on its outer face, coaxial with the armature 14, field windings and pole pieces indicated at 15.

At the end of the armature remote from the impeller 1, the shaft 5 terminates within a journal 17, carried in a thickened central portion of an end plate. Coaxial with the shaft 5, the end plate 18 has a tapped hole in which a set-screw 20 is' received, the set-screw 20 being locked The set-screw 20 locates on the back of a thrust bearing 19 for the shaft 5, Whose position may be adjusted by rotation of said set-screw, so that the performance of the pump can be varied as the impeller 1 will be moved axially downward as the setscrew 20 is screwed home, thus producing more clearance between the impeller and the Wall between the outlet chamber 7 and inlet chamber 8, and vice versa. In this manner movement of the thrust bearing 19 axially relative to the stator 16 of the electric motor enables the axial position of the shaft 5 and the impeller 1 to be adjusted in order to vary the output of the pump assembly, since in operation, the shaft 5 carrying the impeller unit 1 always rests against the thrust bearing 19". The set-screw 20 may incidentally be used for venting the pump when a system in which it is fitted is filled with liquid, and for I freeing the shaft from binding in its bearings after a period of inactivity.

It may be noted that the sleeve 15 is held against the uppermost wall of inlet chamber 8 by a plurality of studs 22 and nuts 23, dispersed around said sleeve 15. Said uppermost wall of inlet chamber 8 is provided with slots 24, covered with filter mesh as indicated at 25, so that liquid from the inlet chamber may flow into the motor chamber 13. Such a flow is in fact induced during operation, as the working face of journal 12 is provided with a number of grooves (not shown) extending parallel to shaft 5 to afford communication between the motor chamber 13 and the inlet chamber 8; as the region in inlet chamber 8 adjacent the shaft 5 is the minimum pressure region (due to the flow of liquid through hole 11 to the impeller 1) a flow of liquid out of (the motor chamber 13 via said grooves is produced, and the liquid thus removed is replaced by liquid entering the motor chamber 13 through the slots 24.

Thus it will be seen that a pump of considerably improved form has been provided, which while it may readily be made more compact than existing pumps of the same general type yet provides for very ready access to the important thrust bearing. It will of course be appreciated that the type of thrust bearing shown in :the drawing is somewhat simple and equally that a variety of types of thrust bearing could be counted in the position shown and that in any case case of access to it is a matter of some weight. Pumps embodying the present invention may be mounted in any position or at any angle, eLg. inverted as compared with the position shown in the drawing, without affecting its operation adversely.

As one example of the variations possible, reference may now be made to FIG. 2 of the drawings, wherein a pump of slightly difierent form is shown. Many parts of this pump are substantially, identical with corresponding parts shown in FIG. 1 and therefore such parts are identified by the same references and will not be further described. However, it will be seen that in the pump of FIG. 2 there is an outer casing 30 of somewhat conical shape and certain parts are arranged to conform with the shape of such casing. A particular difference from the pump of FIG. 1 is in the thrust bearing, and in FIG. 2 it will'be seen that a thrust washer 31,preferably having a steel core and an outer coating of polytetrafluorethylene is retained in contact with the upper end of the shaft by means of a bearing stud 32 whose head33 is in contact with the washer 31. Said stud 32 is carried in a central bore of a cap member 34, the sides of stud 32 having one or more grooves or flats to provide air venting whenever a screwed plug (not shown) is removed from the upper end of the central bore of said cap member 34,

The cap member 34 is threadedly engaged at 35 in a recess in a fixed block 36 carried by the stator componemts of the motor, the threaded connection between member 34 and block 36 being sealed by polytetrafluorethylene tape laid in the co-operating threads and by a sealing ring 37 accommodated in an annular groove in thelower portion of the recess and engaging the lower part of the cap member 34.

The cap member 34 is shown in its uppermost position and it will readily be seen that rotation of said cap member (by means'of a knob 38 keyed to the upper end of said cap member) must cause a downward movement of the Washer 31, and hence of the shaft 5 and impeller 1, thus increasing the clearance between the upper (inlet) face of the impeller and its casing.

Other changes or modifications may also be made without departure from the scope of the invention, thus for example for uses where hi her output pressures are required a second impeller may be included to provide twostage pumping.

I claim:

1. A circulating pump unit of the centrifugal type comprising in combination, an electric motor having a rotor and a stator, a floating shaft to which the, rotor of said motor is secured, a pump assembly secured to one end of said electric motor so that said shaft also extends into said pump assembly, said pump assembly including a housing having an inlet means and an outlet means, an impeller secured directly to said shafit within said pump assembly with its inlet side towards said electric motor, said impcllers inlet side defining a gap with the inlet means of said housing, a single thrust bearing for said electric motor shaft, said bearing being axially movably mounted relative to said stator at the opposite end of said electric motor from said pump assembly, the shaft being held, during operation, against said bearing by the working pressure generated by the impeller and acting upon the area of the undersurface of said impeller, and an operating member mounted externally of the stator of said electric motor and operable to move said bearing axially relative to the stator of said electric motor, either with or against said working pressure generated during operation, so as to enable the axial position of said shaft and said impeller to be adjusted in order to vary the output of said pump assembly, without altering the flow pattern of the output of the pump, by allowing a variable fraction of the pump output to flow back to the inlet side of the impeller through said gap defined by the inlet surface of the impeller and the housing.

2. A circulating pump unit of the centrifugal type as claimed in claim 1 in which the impeller is a single entry impeller and is so placed within the housing of said pump assembly that a channel for a return flow, from the outlet side to the inlet side of said pump assembly, of liquid to be pumped by said unit is defined between a wall of the pump assembly and an adjacent wall of said impeller, adjustment of the axial position of said impeller within said housing causing a variation of the width of said channel.

3. A circulating pump as claimed in claim 1 in which the motor is of the canned rotor type having a fluid :tight casing containing the rotor and being surrounded by the stator, apertures being defined in a wall between the pump assembly and the rotor casing of said electric motor, which apertures permit fluid to pass through said wall and circulate within said rotor casing.

4. A circulating pump as claimed in claim 2 in which the motor is of the canned rotor type having a fluid tight casing containing the rotor and being surrounded by the stator, apertures being defined in a wall between the pump assembly and the rotor casing of said electric motor, which apertures permit fluid to pass through said wall and circulate within said rotor casing.

Reterences Qited in the file of this patent UNITED STATES PATENTS 1,433,037 Reid Oct. 24, 1922 2,107,481 Johnson Feb. 8, 1938 2,468,187 Ericson Apr. 26, 1949 2,517,233 Peters Aug. 1, 1950 2,646,001 Ray July 21, 1953 2,874,642 Forrest Feb. 24, 1959 2,939,399 Rutschi June 7, 1960 3,034,443 Hinrichs et al. May 15, 1962 

1. A CIRCULATING PUMP UNIT OF THE CENTRIFUGAL TYPE COMPRISING IN COMBINATION, AN ELECTRIC MOTOR HAVING A ROTOR AND A STATOR, A FLOATING SHAFT TO WHICH THE ROTOR OF SAID MOTOR IS SECURED A PUMP ASSEMBLY SECURED TO ONE END OF SAID ELECTRIC MOTOR SO THAT SAID SHAFT ALSO EXTENDS INTO A SAID PUMP ASSEMBLY, SAID PUMP ASSEMBLY INCLUDING A HOUSING HAVING AN INLET MEANS AND AN OUTLET MEANS, AN IMPELLER SECURED DIRECTLY TO SAID SHAFT WITHIN SAID PUMP ASSEMBLY WITH ITS INLET SIDE TOWARDS SAID ELECTRIC MOTOR, SAID IMPELLER''S INLET SIDE DEFINING A GAP WITH THE INLET MEANS OF SAID HOUSING, A SINGLE THRUST BEARING FOR SAID ELECTRIC MOTOR SHAFT, SAID BEARING BEING AXIALLY MOVABLY MOUNTED RELATIVE TO SAID STATOR AT THE OPPOSITE END OF SAID ELECTRIC MOTOR FROM SAID PUMP ASSEMBLY, THE SHAFT BEING HELD, DURING OPERATION, AGAINST SAID BEARING BY THE WORKING PRESSURE GENERATED BY THE IMPELLER AND ACTING UPON THE AREA OF THE UNDERSURFACE OF SAID IMPELLER, AND AN OPERATING MEMBER MOUNTED EXTERNALLY OF THE STATOR OF SAID ELECTRIC MOTOR AND OPERABLE TO MOVE SAID BEARING AXIALLY RELATIVE TO THE STATOR OF SAID ELECTRIC MOTOR, EITHER WITH OR AGAINST SAID WORKING PRESSURE GENERATED DURING OPERATION, SO AS TO ENABLE THE AXIAL POSITION OF SAID SHAFT AND SAID IMPELLER TO BE ADJUSTED IN ORDER TO VARY THE OUTPUT OF SAID PUMP ASSEMBLY, WITHOUT ALTERING THE FLOW PATTERN OF THE OUTPUT OF THE PUMP, BY ALLOWING A VARIABLE FRACTION OF THE PUMP OUTPUT TO FLOW BACK TO THE INLET SIDE OF THE IMPELLER THROUGH SAID GAP DEFINED BY THE INLET SURFACE OF THE IMPELLER AND THE HOUSING. 